The invention relates to a navigation method and a navigation device. In modern motor vehicles, navigation devices are usually provided. These enable determination of a route between a starting point and a destination point and then route guidance toward the destination point taking into account a currently detected position that is determined regularly by means of a GPS system. The navigation devices are usually designed to determine a route while taking various optimization criteria into account. For instance, a provision can be made to determine the fastest or shortest route between the starting point and the destination point, or also to determine a route that preferably has a certain type of road, such as highways, for example, or to determine a route that particularly has toll-free stretches. Increasingly, it is also desired to take the expected energy requirement into account when determining a driving route.
For instance, from the article “Spart ein Navi wirklich Kraftstoff?” [“Does a navi[gational system really save fuel?”], Auto Motor and Sport, http:www.auto-motor-und-sport.de/testbericht/sparen-navigationsgeraete-wirklich-kraftstoff-1477779.html, downloaded on May 31, 2011, it is known to determine a most efficient route. A description is given in the article of taking into account whether the respective vehicle is equipped with a start-stop or hybrid system. One consequence of this may then be that the driver is more likely piloted through the city in this case than with a car in which the engine continues to run at red lights. Moreover, it is also explained in the above-mentioned article that mountains increase energy consumption far less in a hybrid model, since energy is recovered during descents, whereas a conventional combustion engine should run as uniformly as possible on level ground. It is also explained in the above-mentioned article that current systems are only capable of making a compromise between the length of the route and the driving time. Differences in altitude are not yet taken into account.
It is one object of the invention to provide a navigation method and navigation device that make a contribution to precisely detecting the expected energy requirement for a predetermined route.
It is another object of the invention to provide a navigation method and a navigation device that make a contribution to determining a route taking into account a precise expected energy requirement.
This and other objects are achieved according to a first aspect of the invention by a navigation method in which a constant travel characteristic is determined that is representative of a vehicle-specific energy requirement with respect to a predetermined trip length and quasi-constant speed, particularly constant speed, on a quasi-level route, particularly a level route. The reference to the predetermined trip length can be a reference per meter or kilometer driven, for example.
Furthermore, at least one dynamic characteristic is determined that is representative of a vehicle-specific energy requirement with respect to a predetermined trip length at a predetermined quasi-dynamic speed, particularly a dynamic speed, on a quasi-level route, particularly a level route.
The constant travel characteristic is adapted in each case depending on at least one vehicle-specifically determined energy requirement characteristic for a traveled route segment that has been recognized as being quasi-level and in which a quasi-constant speed has been recognized.
The energy consumption characteristic can be determined, for example, on the basis of a metered quantity of fuel determined on the respectively traveled route segment and/or on the basis of a required electrical power determined for the traveled route segment.
In this context, in order to determine the expected energy requirement for a predetermined route for each route segment, an estimated segment energy requirement characteristic is determined based on a respective constant travel characteristic that is associated with the respective route segment and, in the event that one or more dynamic events are associated with the respective route segment, for each dynamic event depending on a respective dynamic characteristic.
An estimated route energy requirement characteristic for the predetermined route is determined based on the respective segment energy requirement characteristics.
In particular, the insight is exploited in this context that dynamic events are responsible to a great extent for over-consumption compared to assumed constant travel. Beyond that, however, an energy profile during travel is vehicle-specific and differs.
Optionally, the dynamic characteristic is adapted in each case based on at least one energy consumption characteristic determined on a vehicle-specific basis for a route segment traveled in which at least one predetermined speed dynamic has been detected and was recognized as being quasi-level.
In this context, it is also especially advantageous if the constant travel characteristic and/or the dynamic characteristic is detected and adapted in a driver-specific manner, thus taking into account different behavior of the driver, which can have a substantial impact on the energy requirement.
In this way, the expected vehicle-specific energy requirement can be estimated in an especially precise manner for a respective route.
Besides determining a route between the starting point and the respective destination point with the lowest expected energy requirement for the vehicle, the above procedure also makes it possible to indicate a possible range of the vehicle with respect to fueling and/or charging that might be necessary over the course of the route.
Through the respective adaptation of the respective constant travel characteristic and/or of the respective dynamic characteristic, a learning of the respective characteristics is enabled, and time-related changes that result, for example, from changed driving behavior or a change in a vehicle-specific consumption characteristic can also be taken into account.
According to a second aspect, the invention is characterized by a navigation method for a vehicle in which the detection and adaptation of the at least one constant travel characteristic and of the at least one dynamic characteristic is performed according to the first aspect.
To determine a driving route between a predetermined starting point and a predetermined destination point while taking an expected energy requirement into account, it is determined for each candidate route segment whether one or more dynamic events are associated with it, and an estimated candidate route energy requirement characteristic is also determined for each candidate route segment on the basis of a respective constant travel characteristic that is associated with the respective candidate route segment and, if one or more dynamic events are associated with the respective candidate route segment, for each dynamic event based on a respective dynamic characteristic.
Furthermore, the driving route is determined by selecting the candidate route segments on the basis of the estimated candidate route energy requirement characteristics. The second aspect corresponds to the first aspect in terms of its effects and advantages.
According to an advantageous embodiment of the second aspect, the driving route is determined by selecting the candidate route segments while taking an estimated segment driving time for the respective candidate route segments into account. In this way, the driving route can be determined such that its driving time also lies within a range that is acceptable to the driver.
According to an advantageous embodiment of the second aspect, the driving route is determined by selecting the candidate route segments while taking a vehicle load energy requirement characteristic into account that is determined on the basis of an estimated driving time for the driving route.
The vehicle load energy requirement characteristic is particularly representative of an expected energy requirement of respective vehicle loads, such as vehicle heating and/or air conditioning, for example.
According to an advantageous embodiment of the first aspect, the estimated route energy requirement characteristic is determined on the basis of a vehicle load energy requirement characteristic, which is determined based on an estimated driving time for the driving route.
According to another advantageous embodiment, the vehicle load energy requirement characteristic is determined on the basis of a detected outside temperature.
According to another advantageous embodiment, the constant travel characteristic is respectively determined with respect to one of several predetermined speed classes. The constant travel characteristic of a respective speed class is adapted in each case at a speed lying within the speed class. In this way, it can be ensured in a simple manner that, if the speed classes are selected appropriately, adaptation takes place with sufficient frequency, making it possible for the respective constant travel characteristic to be learned as precisely as possible. On the other hand, this ensures that different characteristics can be taken into account for different speed classes.
According to another advantageous embodiment, the dynamic characteristic is determined in each case with respect to one of several predetermined speed change classes. The dynamic characteristic of a respective speed change class is adapted in each case with a speed change that lies within the speed change class.
In this way, it can also be ensured that, if the speed change classes are selected appropriately, the respective dynamic characteristic is adapted with sufficient frequency, thus enabling good learning thereof. Moreover, a different characteristic can be taken into account here as well with respect to the respective speed change class.
What is more, this is based on the insight that, particularly with differing speed change classes, which is to say different speed change ranges, another characteristic of the energy requirement to be expected is regularly present.
According to another advantageous embodiment, the dynamic characteristic is adapted and detected separately in each case for a positive and a negative acceleration, the dynamic characteristic for the positive and negative acceleration each being adapted in the case of a positive or negative acceleration, respectively.
In particular, the different influences on the energy requirement in the event of positive acceleration and also in the event of negative acceleration, which is to say during braking in particular, can be precisely taken into account in this way.
According to another advantageous embodiment, the dynamic characteristic is adapted on the basis of the respective constant travel characteristic to the respective speed class under which an average speed expected for the traveled route segment falls. In this way, particularly, an expected increased or reduced energy requirement can be determined with respect to constant travel.
According to an advantageous embodiment of the first aspect, a factor is respectively determined and adapted in order to adapt to a predetermined characteristic that reflects a relationship between speed and energy requirements for the respective speed class. In this context, the energy requirement can represent, for example, the fuel consumption and/or the electrical consumption or the like. The factor particularly represents the respective constant travel characteristic in this context.
In this way, the respective route segment energy requirement characteristic can be determined with particular precision since, on the one hand, the factor is learned for the respective speed class and can therefore be adapted with commensurate frequency, and the respective energy requirement can also be determined in a differentiated manner, represented by the respective characteristic.
According to another advantageous embodiment, the detection of the predetermined dynamic is performed on the basis of a detected change in speed, a detected steering angle, a detected braking pressure, an accelerator pedal position and/or a clutch state. In this way, it is possible to detect the predetermined dynamic in a simple and precise manner, particularly using already existing sensors.
According to another advantageous embodiment, the constant travel characteristic to be associated with the respective route segment or candidate route segment is determined on the basis of an expected average speed for the respective route segment or candidate route segment. The expected average speed can be determined, for example, on the basis of historical measured data for the speed on the respective route segment, or it can also be simply predetermined. In this context, it can also be predetermined, for example, based on the time of day or even based on external information made available to the respective vehicle, such as the current traffic situation.
According to another advantageous embodiment, a respective dynamic event is allocated if an expected change in speed exceeds a predetermined speed change threshold. Moreover, the dynamic characteristic to be allocated for the respective dynamic event is determined based on an expected change in speed during the respective dynamic event.
In this context, it is especially advantageous if the expected change in speed is determined based on an expected turning angle. This is particularly advantageous if digital map information that is made available does not contain any explicit information regarding the expected change in speed for the route segment. In this context, the insight is utilized that the respective expected turning angle correlates with the change in speed to be expected.
According to another advantageous embodiment, the expected change in speed is determined on the basis of a road intersection characteristic. In this way as well, this expected change in speed can be determined quite easily from the road intersection characteristic, which can particularly be derived from the existing map data, particularly in the absence of explicit information on the change in speed to be expected for the respective route segment.
In this context, it is especially advantageous if the road intersection characteristic is determined on the basis of the road types of the intersecting roads, traffic signs at the respective intersection and/or the presence of a traffic light at the respective intersection. In this context, the insight is utilized that, depending on the interplay of the different road types—for example, main road, secondary road, or the like—the change in speed that will occur at the respective intersection can be estimated with a high degree of likelihood. This also applies, accordingly, to the respective traffic signs, such as Yield, Stop, or the like, or the presence or absence of a traffic signal.
According to another advantageous embodiment, the expected change in speed is determined on the basis of a detected curve characteristic.
According to another advantageous embodiment of the first aspect, a grade characteristic is determined for each route segment that is representative of a grade-dependent adjustment of the energy requirement of the vehicle as a function of a predetermined grade for the route segment. For each route segment, the estimated route segment energy requirement characteristic is determined taking the respective grade characteristic into account.
In this way, an increased energy requirement to be expected in the case of a positive grade can be taken into account, and in the case of a negative (or downhill) grade, a reduced energy requirement can be accounted for. Moreover, through the grade-dependent determination of the grade characteristic, it can be ensured that the energy requirement is adjusted to different degrees for different grades. In this context, it can then also be taken into account, for example, that a recuperation of the released potential energy and storage thereof in a vehicle battery is only possible to a reduced extent in the case of an especially pronounced negative grade, since it is expected that the driver will need to apply the brakes more.
It can be especially advantageous in this context if the grade characteristic is respectively predetermined for several grade ranges.
According to another advantageous embodiment of the second aspect, a grade characteristic is determined for each candidate route segment that is representative of a grade-dependent adaptation of the energy requirement of the vehicle as a function of a predetermined grade for the candidate route segment. For each candidate route segment, the estimated candidate route energy requirement characteristic is determined taking the respective grade characteristic into account.
According to another advantageous embodiment, the grade characteristic is adapted in each case as a function of at least one vehicle-specifically determined energy consumption characteristic for a traveled route segment that is recognized as having at least one predetermined grade.
According to another advantageous embodiment, the estimated route energy requirement characteristic is corrected for the predetermined driving route as a function of an engine temperature and a route length. In this way, a warm-up behavior of the engine can be taken into account, particularly when departing in the cold and in the case of a short planned route.
According to a second aspect, a navigation device is provided that is designed to carry out the navigation method according to the first aspect and, in this regard, also with respect to its advantageous designs. In this context, the navigation device particularly includes a data and/or program memory and a processing unit, which particularly comprises a microprocessor. In terms of its advantages and advantageous designs, the second aspect corresponds to the first aspect.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.